How much to tip
If you ask 10 people how much to tip in a given situation, you'll get several answers and a slew of hot-headed opinions about the "right" thing to do.

To help start your next debate, here's a quick guide to customary gratuities for various services. The guide is provided by the Emily Post Institute. Those with passionate views about how much to tip the pizza-delivery guy, please see the information in the footnote provided by two other sources.

(For a look at the real reasons we tip and whether tipping has anything to do with the quality of service we receive, click here.)

RESTAURANTS/BARS

Waiter/waitress:

15% of bill (excl. tax) for adequate service; 20% for very good service; no less than 10% for poor service

Headwaiter/captain:

often gets a cut of table server's tip; so tip your server extra to reward captain, or tip captain separately

Sommelier, or wine steward:

15% of cost of the bottle

Bartender:

15% to 20% of the tab, with a minimum of 50 cents per soft drink, $1 per alcoholic drink

Coatroom attendant:

$1 per coat

Parking valet or garage attendant:

$2 to bring your car to you

Washroom attendant:

50 cents to $1

DAILY LIFE

Taxi driver:

Varies depending on locality. Assume 15% will be enough; an extra $1 to $2 for help with bags.

Food delivery person:*

10% of the bill (excl. tax), at least $1 for bills up to $10. Should tip 15%-20% for a difficult delivery.

Grocery loader:

Check with store policy if tips are accepted. If so, $1 for bringing bags to car; $1.50 to $3 if you have more than 3 bags.

Barber:

15% to 20%, minimum $1, for a haircut. For other services (shampoo, shave or manicure) tip $1 to $2 to service provider.

Hairdresser:

15% to 20%. (It is now acceptable to tip owner, unless he or she says otherwise.)

Shampoo person:

$2

Manicurist:

15%

Spa service (e.g., massage):

15% to 20%. If service is provided by owner, no tip.

Staff at coffee/food retailers with tip jars:

No tip required. It's completely optional.

Handyman:

No tip

Gas attendant:

No tip

* Mike Lynn, associate professor of consumer behavior at the Cornell Hotel School suggests tipping pizza delivery folk a minimum of $2 per pizza. His reasoning: Food delivery can be dangerous if delivering to crime-ridden neighborhoods or driving in bad weather, etc. The Web site www.tipthepizzaguy.com suggests the following: 15% for normal service, with a $2 minimum; 20% for excellent service; 10% or less for poor service; at least 10% for orders of $50 or more. Don't assume a delivery charge, if there is one, goes to the pizza deliverer. Ask the person who takes your order.

TRAVEL

Skycap at airport:

$1 per bag if you check-in curbside; $2 per bag if skycap takes bags to check-in counter.

Hotel doorman:

$1 per bag for help with luggage; $1 per person for hailing a cab

Hotel bellhop:

$1 per bag for bringing luggage to your room (but a $2 minimum if you have just one bag)

Hotel housekeeper:

$2 to $5* per night

Hotel concierge:

$5 for getting you tickets or reservations ($10-plus if they're hard to get). No tip required when you ask for directions.